Field of the Invention
The invention generally relates to a Multi-SIM user equipment technology, and more particularly, to the Multi-SIM calls with carrier aggregation (CA) and/or dual connectivity (DuCo).
Description of the Related Art
Wireless communication systems have been widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Teletransmissions System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrums, and integrating better with other open standards using OFDMA on downlinks (DL), and SC-FDMA on uplinks (UL) and multiple-input multiple-output (MIMO) antenna technology.
A Multi-SIM wireless communication device may be one which holds two SIM cards, which means that the device can handle two different network services. Each network service can be assigned to a different account or telephone number. In wireless devices that include only one transceiver, only one of the two subscriptions may be transmitting or receiving radio frequency (RF) signals at a time. Such devices are referred to as Dual SIM Dual Standby (DSDS) devices, since while one service is actively transmitting or receiving the other service is put on standby. In contrast, in wireless devices that include two transceivers and two SIM cards, referred to as Dual SIM Dual Active (DSDA) devices, both services may be actively transmitting or receiving at the same time.
In a traditional DSDS device, if a PS call is ongoing over the first SIM card, the DSDS device may not monitor or ignore incoming MT (Mobile Terminated) PS call or MT CS call notification (i.e. paging message) received on the second SIM card. Therefore, how to adopt a flexible mechanism for the user to obtain the call information (e.g. caller number) corresponding to the MT PS call or MT CS call received on the second SIM card, or decide whether to pick up the MT PS call or MT CS call from the second SIM card, is a subject worthy of discussion. In addition, in a traditional DSDA device, the DSDA device needs to duplicate additional hardware for another SIM card before activating the dual voice call. This may result in additional costs for the duplicated hardware.